Family Poaceae - Subfamily Pooideae

• cool season grasses predominant in higher latitudes and bearing a predominantly membraneous ligule
• distinct morphologies that are often used in the paleo-ecological literature to infer cool temperate habitats (distinctive embryo that is very small relative to the size of the mature grain, root hairs from short epidermal cells, silica cells or phytoliths that are often sinuate, leaves lacking microscopic hairs)
• a base chromosome number of x=7 (except in the tribe Meliceae). This means that diploids have somatic chromosome numbers of 14 whereas tetraploids have 28, etc.

Tribe Triticeae (already introduced)
1. A two sided terminal spike with the spikelets laterally placed along the main rachis (i.e., the sides of the spikelets face the main rachis). 2. the glumes are often small, narrow, or transformed into an awn (excepting Triticum and Aegilops with broad glumes having an acentric midrib).

• Agropyron: perennial, mostly one spikelet per node, midrib of lemmas in line with midribs of glumes
• Elymus: perennial, mostly 2 (or more) spikelets per node, florets about 90 degrees out of alignment with glumes
• Eremopyron: annual, one spikelet per node, spikelets diverging and wide angles and arranged on very short internodes (like Ag. cristatum)
• Hordeum: mostly perennial, 3 spikelets per node, 1 floret per spikelet, the two lateral spikelets at each node pedicellate and bearing sterile florets (except in six-row barely)
• Secale: annual, ciliate hairs on lemma margins, inflorescence rachis always disarticulating at nodes
• Taeniatherum: annual, two spikelets at a node, one floret per spikelet, glumes awn-like (like Hordeum except two spikelets per node)
• Triticum and Aegilops: annual, ovate glumes with usually an apical notch and an acentric midrib

Tribe Aveneae
1. nearly always large glumes. 2. many genera have awns from back of lemma (trait only found in this tribe). 3. tendency to have contracted or spicate panicles

• Agrostis: small spikelets rarely over 3 mm long and containing one floret, glumes with a sawtoothed (scabrous) midrib
• Alopecurus: dense spicate panicle, disarticulation below the glumes, unawned glumes that are fused at the base, lemma awned from back
• Avena: open panicle, large spikelets usually well over 1 cm long
• Beckmannia: contracted one-sided panicle, oval spikelets stack together like pancakes
• Calamogrostis: like Agrostis but the single floret with a callus bearing long straight hairs and glumes lacking the sawtoothed midrib
• Deschampsia: small spikelets with two florets, each bearing an awn from near the lower part of the lemma
• Hierochloe: small spikelets as broad as long, bearing three florests, the lower two of which are larger and hairier (and staminate) compared to the upper hardened fertile floret
• Helictotrichon: similar to Avena but the spikelets are not quite as large, typically about 1 cm long, and the lemma awn comes off below the midpoint near the base, and the inflorescence is a contracted spike
• Holcus: small spikelets with two florets per spikelet, the lower floret bears a short hooked awn
• Koeleria: contracted panicle, spikelet with mostly 2 florets and no awns on glumes or lemmas, paleas clear, colorless (one of the few Aveneae in the region to have spikelets with two or more similar florets that lack awns)
• Phalaris: like Hierochloe but the spikelets are longer than broad and the lower staminate florets are inconspicuous and hairy, or very large and hairless
• Phleum: dense spicate panicle, disarticulation above glumes, glumes abruptly short awned and free to the base, lemmas not awned
• Polypogon: inflorescence a dense spike bearing many small spikets, the awns coming off of the glumes are over 10x the length of the lemma
• Trisetum: like Deschampsia but the lemmas awned from above the midpoint towards the tip
• Ventenata: annual with very open diffuse spikets, the first floret with a straight awn, and the next floret or two with a twisted bent awn.

Tribe Stipeae
1. indurate lemma that is tightly rolled around the palea and flower; the lemma thus simulates a seed coat. 2. a long awn from the tip of the lemma. 3. strictly 1 floret per spikelet. 4. large glumes (comparable to Aveneae, but note that Aveneae can have more than one floret per spikelet and has a long awn emanating from the back or lower two-thirds of the lemma.

• Oryzopsis: lemma with deciduous awn, body of floret ovate, callus of floret mostly blunt
• Stipa: lemma with persistent awn, body of floret elongate, callus of floret mostly sharp

Tribe Meliceae
1. prominently ribbed lemmas. 2. closed leaf sheath (see Bromus of tribe Poeae also). 3. Aquatic or semi-aquatic (except Melica, onion grass). 4. base chromosome number of x = 8, 9, or 10 (diploids have somatic chromosome numbers of 16, 18, or 20, whereas tetraploids have 32, 36, or 40.

· Catabrosa: 2-3 well spaced florets per spikelet, prominent lemma veins even and parallel, aquatic, base of stem rooting at nodes

· Glyceria: more than 3 tightly overlapping florets per spikelet, prominent lemma veins even and parallel, riparian, base of stem from rhizomes

· Melica: more than 3 tightly overlapping florets per spikelet, prominent lemma veins uneven or not parallel, dry site, base of stem with a bulb or corm

Tribe Poeae
1. No distinctive traits distinguish this tribe and for our purpose, membership in this tribe is defined by not belonging to one of the other four tribes of Pooideae.

• Bromus: closed leaf sheath (see Meliceae a tribe with essentially glabrous lemmas which stand in contrast to the usually hairy lemmas of Bromus), palea and grain firmly adherent (pp. 158-160)
• Dactylis: contracted secund panicle (compare to Beckmannia, Tribe Aveneae), keeled leaf sheaths, often folded leaves
• Festuca: florets round on the back and distinctly separated along the rachilla, ligule usually (not in all species) bilobed and distinctly visible from side view
• Lolium: terminal 2-sided spike but with the spikelets placed ‘edgewise’ or with the backs of the lemmas facing the main rachis, spikelets with only one glume (except the terminal spikelet)
• Poa: leaf blades with prowlike tips, as well as with two prominent lines on either side of the midrib on the upper blade surface (cf. 'railroad tracks'), no awns from glumes or lemmas in contrast to Festuca and Bromus
• Puccinellia: spikelets like those of Meliceae but lemmas with veins not so prominent, alkaline-site inhabiting, the spikelets closely appressed to the panicle branches
• Vulpia: like Festuca but annual, the spikelets in a subtly secund arrangement

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